As advances continue to be made in the area of semiconductor memory devices, high capacity and low cost are increasingly important. In particular, memory cell designs having small footprints are increasingly desired to provide high density. For this reason, diode arrays are increasingly finding utility in memory designs. However, because of leakage currents in diode arrays, increasingly large arrays often result in non-negligible total leakage currents. These leakage currents may grow geometrically with the size of the array, resulting in higher power consumption. U.S. Pat. No. 7,376,008 (“the '008 patent”) describes this cumulative leakage problem in detail, and the entire disclosure thereof is incorporated by reference herein. To deal with this leakage problem, diode array memories can be broken down into multiple tiles or sub-arrays such that only a portion of the entire array is energized at a given point in time. However, each sub-array or tile typically requires some peripheral support circuitry and, as a result, will contribute to a reduction in array efficiency. The '008 patent addresses this problem through the use of current-level switching devices (CLSDs) and describes that when only a single row and a single column are energized, with the remaining (i.e., non-selected) rows and columns floating, the total current leakage grows only linearly with the size of the array. However, CLSDs switch when a voltage level is exceeded and, as such, have analog characteristics—i.e., they are not purely digital devices. Many memory-design engineers are skilled in digital logic design, but fewer engineers are trained in analog design. Thus, the increasing use of CLSDs leads to increased design complexity, time, and expense.
Thus, a device more digital than CLSDs that facilitates low power consumption by minimizing leakage currents is highly desirable. Furthermore, such a memory device should be inexpensive to manufacture and should utilize existing manufacturing tools and techniques while avoiding the use of materials that might contaminate manufacturing equipment.